A peg is used in a stringed instrument such as a guitar in the art to wind and unwind a string utilizing a mated worm and worm wheel. The worm is arranged in coaxial with a knob, and the worm wheel is arranged in coaxial with a string attachment. The peg of this kind comprises, as shown in FIGS. 6 and 7, a housing 52 generally secured at the head on the stringed instrument; a worm rod 58 having a worm 54 rotatable on the same axis in the housing 52 and having a knob 56 provided at one end of the rod 58 outside the housing 52; and a winding rod 64 having a worm wheel 60 mated with the worm 54 and rotatable on the same axis in the housing 52, and having a string attachment 62 formed at one end of the rod 64 outside the housing 52. The peg 50 of this kind is configured to wind and unwind a string by rotating the knob 56 to rotate the worm 54, which in turn rotates the worm wheel 60, thereby rotating the winding rod 64.
Such the peg 50 for stringed instruments utilizing the mated worm 54 and worm wheel 60 is different in purpose for use from a decelerator mechanism used in various machines, and has a purpose for tuning the string. Therefore, there are restrictions on the attachment and usage of the peg because of the frequent use of one portion of the worm and worm wheel and the specialty of the stringed instrument. Accordingly, it is required to provide a larger mating clearance (gap) between the worm and the worm wheel than those in other various machines.
In order to allow the thus configured worm 54 and worm wheel 60 to rotate smoothly, special lead angles are given to grooves of the worm 54 and teeth of the worm wheel 60. In addition, a clearance A at the mating portion between the worm 54 and the worm wheel 60 is formed slightly larger. When the thus mated worm 54 is rotated, a surface of the groove of the worm 54 is press-contacted with a surface of the tooth of the worm wheel 60, resulting in a friction force, which rotates the worm wheel 60 smoothly. In this case, the press-contacted surfaces of the worm 54 and the worm wheel 60 suffer from friction heat due to rotations and may seize up possibly. Therefore, the worm 54 is generally composed of a harder material and the worm wheel 60 a slightly softer material to prevent both from seizing up. Through frequent tuning and long-term use, however, the tooth surface of the worm wheel 60 is worn to reduce durability thereof. In addition, when the worm rod 58 rotates, friction heat arises at a portion between the worm rod 58 and its rolling bearing. The friction heat may also cause the worm rod 58 to seize up possibly.
With respect to the portion of the rolling bearing around the worm 54 and the mating portion between the worm 54 and the worm wheel 60, it is required to prevent them from seizing up and achieving their smooth rotations using a certain means. As that means, a lubricant, including grease and lubricating oil, (hereinafter referred to as a “fluid lubricant”) is injected into the mating portion and into the worm rod 58 and its bearing. If the fluid lubricant adheres to a worker's hand while assembling the peg, and the adhered fluid lubricant then adheres to the body of the peg 50 or the knob 56, much expense in time and effort may be required to sweep out the adhered fluid lubricant from them. In addition, when the peg 50 is attached to the instrument, dirt and wood chips in the factory may adhere to the peg 50 and contaminate the worker's hand. The contaminated hand frequently contaminates the whole instrument, which requires a long period of time to be cleaned up. In particular, a mat-painted instrument requires extremely careful handling, which inevitably produces a loss in assemble time.
When a player employs the peg 50 for tuning, the touch felt at the player's finger is required as gentle and smooth as possible. The fluid lubricant, however, is naturally deteriorated. Accordingly, it can not retain the touch for a long term. In addition, it may invite a trouble to the smooth rotation of the worm 54 and the worm wheel 60. Further, in the conventional peg 50 of this type, as described above, the larger clearance A is formed at the mating portion between the worm 54 and the worm wheel 60. The presence of such the larger clearance A produces a large backlash in the normal direction during frequent winding and unwinding for tuning. As a result, a problem arises because the large backlash not only makes it uneasy to achieve fine-tuning but also makes it difficult to achieve re-tuning by the player during a performance.
As described above, the presence of the larger clearance A between the groove of the worm 54 and the tooth of the worm wheel 60 produces a backlash in the normal direction during winding and unwinding of the string. Due to the backlash, it is inevitable for the worm 54 to rotate ineffectively during winding and unwinding of the string while the tooth of the worm wheel 60 relatively travels over the backlash in the normal direction. Therefore, the operation of the knob 56 is not synchronized with the rotation of the winding rod 64 at the beginning of the operation of the knob 56, resulting in a strange feeling on fine-tuning and a difficulty for the player to achieve re-tuning during a performance.
The backlash in the normal direction is shown in FIG. 7 with the symbol A′. When the worm 54 is rotated in the direction of winding the string (the worm wheel 60 clockwise), for example, one wall 54a of the worm 54 is press-contacted with a tooth 60a of the worm wheel 60. Accordingly, the backlash is formed between the non-contact side of the tooth 60a of the worm wheel 60 and the other wall 54b opposing thereto. The backlash A′ in the normal direction is generally retained in the current state when the worm wheel 60 is in the state of winding the string because the worm 54 is held by the friction force from the bearing and the like that effects on the worm. When the worm 54 is rotated in the direction of unwinding the string (the worm wheel 60 counterclockwise) to the contrary, the tooth 60a of the worm wheel 60 is required to travel over the backlash A′ in the normal direction in order to press-contact the tooth 60a of the worm wheel 60 with the non-contact wall 54b in a groove 54c of the worm 54. Therefore, a time lag occurs between the starting point of operating the knob 56 and the starting point of unwinding the string. The length of this time lag may disturb the feeling on fine-tuning.
The present invention has an object to provide a peg for stringed instruments. This peg requires no fluid lubricant injected into the mating portion between the worm and the worm wheel to achieve smooth rotations of the worm and the worm wheel even if the mating clearance (the backlash in the normal direction) between the worm and the worm wheel is minimized. In addition, the peg is possible to reduce rotational errors caused by the backlash during tuning and re-tuning as low as possible to allow a player to easily achieve fine-tuning even during a performance. Further, the peg is possible to greatly simplify the work for attaching the peg to the instrument and improve the work efficiency. Furthermore, the peg is possible to reduce the friction at the mating portion between the worm and the worm wheel and the friction between the worm rod and its rolling bearing during even frequent winding and unwinding to decrease their abrasion as low as possible so as to give durability to the peg.